The Role of Duplex Ultrasound in Detecting Graft Thrombosis and Endoleak after Endovascular Aortic Repair for Abdominal Aneurysm

Background: To assess the role of duplex ultrasound (DUS) in detecting endoleaks (ELs) and graft thrombosis (GT) in a cohort of patients submitted to endovascular aortic repair (EVAR) for elective infrarenal abdominal aortic aneurysm (AAA) in 2 centers.

Methods: Data, of all consecutive patients treated in 2 operative units of vascular surgery, from January 01, 2000 to December 31, 2016, were retrospectively collected and evaluated. Follow-up data were analyzed to evaluate survival and device-related complications, both at 30-day and in the midterm. The results of computed tomography angiography (CTA) and DUS which were performed yearly, with a time interval between the 2 examinations lower than 30 days, were paired in terms of maximum transverse diameters of the aneurysmal sac, identification of EL, and of GT. Sensibility (SE), specificity (SP), positive predictive value (PPV), negative predictive value (NPV), and accuracy (ACC) of the DUS were calculated with respect to data of each paired CTA and to data of the real clinical diagnosis of either EL or GT. A Student's t-test was performed to compare the aneurysmal sac diameters measured with DUS to those of CTA. "Kappa" coefficient of agreement was also calculated. A P value < 0.05 was the level reference for statistical significance.

Results: A total of 920 patients (104 female, 11.3%) underwent EVAR for elective infrarenal AAA. Technical success was achieved in 910 cases (98.9%). At 30 days, there were 5 deaths (0.5%), no GT, and 3 small type II ELs which did not require any adjunctive procedure. Mean follow-up was 64.8 months (range 1-120.3 months). Survival and freedom from complications were estimated to be 78.4% ± 1.9% and 48.3% ± 1.7%, respectively, at 10 years. Seventy-six more ELs and 8 GTs were recorded. Considering the CTA as the gold standard, SE, SP, and ACC of DUS in the detection of the EL were 93.2% ± 5.8%, 98.8% ± 1.1%, and 97.8%, respectively, with a PPV of 94.5% ± 5.2% and a NPV of 98.3% ± 1.4%. Considering, however, the real diagnosis of the EL, SE, SP, and ACC of DUS were slightly lower (89.4% ± 6.9%, 98.5% ± 1.3%, and 96.9%, respectively), as well as PPV and NPV (93.1% ± 5.8% and 97.7% ± 1.6%, respectively). K coefficient of agreement between the measurements of the sac maximum transverse diameter recorded at DUS and CTA was 0.91, with a little underestimation of the aneurysm diameter at DUS if compared with CTA (mean diameter difference of 2.5 mm, 95% confidence interval: 2.25-2.75 mm).

Conclusions: DUS has proven to be a reliable examination in identifying all GT and most ELs after EVAR, compared with CTA. A good correlation was also observed between the measurements of the sac maximum transverse diameter recorded at DUS and CTA, with a little underestimation of the aneurysm diameter at DUS compared with CTA.